Sacrificial polymer compositions that include polycarbonates, such as, poly(propylene carbonate) are known. Typically such a sacrificial polymer composition can be applied to a substrate, patterned and overcoated with a non-sacrificial material. The overcoated, patterned sacrificial polymer composition can then be exposed to conditions of an elevated temperature sufficient to cause the sacrificial polymer to decompose and further cause decomposition products to pass through the non-sacrificial overcoat, thereby forming a defined enclosed space or air gap.
Sacrificial polymer compositions that include acyclic polycarbonates typically have glass transition temperature (Tg) values of less than 100° C., or less than or equal to 50° C. Such low Tg values are generally accompanied by a combination of, desirably reduced temperatures at which the patterned sacrificial polymer composition is converted into a gaseous phase, and undesirably poor retention of pattern fidelity. The poor retention of pattern fidelity generally limits the extent to which photolithographic methods can be used to form the defined spaces, such as, enclosed microchannels. In the case of enclosed microchannels, for example, poor retention of pattern fidelity can result in microchannels having low resolution and/or undesirable cross-sectional shapes.
U.S. Pat. No. 4,950,736 discloses polycarbonates that are prepared from bicyclol polycyclo dimethanols. The '736 patent does not disclose or suggest the stereochemistry of the bicyclol polycyclo dimethanols. The polycarbonates of the '736 patent are disclosed as having excellent thermal resistance.
It would be desirable to develop new polycarbonate polymers and sacrificial compositions containing such newly developed polycarbonate polymers, that provide a combination of desirable properties, such as Tg values of greater than or equal to 50° C., reduced temperatures at which the patterned sacrificial polymer composition is converted into a gaseous phase, and improved retention of pattern fidelity. In addition, it would be desirable that such newly developed polycarbonate polymers and sacrificial compositions result in minimal residue formation after the polycarbonate polymer of the sacrificial polymer composition has been converted into a gaseous phase. It would be further desirable that such newly developed polycarbonate polymers and sacrificial compositions can be used for temporarily bonding substrates to one another.